I'm trying to do my very first table top out of hardwood but it proving to be quite the learning curve. I acquired a small benchtop jointer and a lunchbox type thickness planer and I've more or less successfully made my boards. What I'm struggling with now is getting a nice glue up without gaps. My first try turned out so so, and i was afraid i didn't use enough glue so I re ripped the joints with my tracksaw. I think my boards are evenly thick but they seem a bit hourglass shaped if that makes sense. They'reb about 170cm long and they join up on the ends, but there's about a 1mm gap towards the middle on some joints and its too much to squeeze all the gaps together on the panel. I first tried jointing on the benchtop jointer but got horrible results with the small bed. (Could also be lack of skill as this is all new to me). I then went with a tracksaw and parallel guides instead,which is better but still giving me a bit of a gap. So I guess im asking how more experienced woodworkers would proceed.
Would it help to glue up two boards at a time so there's maybe enough strength in the clamps to squeeze the gap shut. Or should i rip the bigger boards down so they all fit upright in the thickness planer and try to get two really parallel sides that way? I have rollers to extend the beds of both the thicknesser and the jointer but have had better results with the thicknesses. Is there something else I'm not thinking of?
Thanks I actually used the up down method with the track saw but from my understanding that's more about the board edges not being 90° which seems to nut be an issue when i measure it, but the hourglass shape wouldn't be affected by that right?
The up/down method (or in/out method on a jointer, same idea) is for compensating for any out-of-square condition of the tool.
like, I'm pretty sure my jointer's fence will never be set to 90.000000000000000 degrees to the table. The pre-Trump US office of Weights and Measures couldn't manage it, partially because it's a piece of aluminum almost flexible as my house cat. I'm certainly not going to get it perfect armed with the combination square I keep in my tool belt.
Let's say I get it set to 91.0 degrees. Put one board face into the fence, the other face out of the fence, I'll have cut one of them at 91 degrees and the other at 89. These are complementary angles and together they add up to 180. Paul Sellers planing both boards at the same time achieves a similar effect.
This would compensate for, say, an imperfection in the bevel setting of your tracksaw; if the blade is set to a 90.234572 angle instead of 90.00000, the up/down method will compensate for that. But it won't compensate for, say, if the frame of the track saw isn't perfectly rigid and you apply a little bit of side pressure flexing the foot a little partway through the cut. Track saws are usually better about that than normal circular saws, but still.
Also, did you buy this stock rough and surface it yourself on that jointer and your lunchbox planer? Because surface planing a long board on a benchtop jointer will have the same problems as edge jointing on one. I don't know how flexible your tracksaw's track is but if it conforms even slightly to a twisted board you might get an imperfect cut.
Can you take pictures? It may help with a more definite diagnosis.
That's true. The only thing I can think of for getting an hourglass shape would be potentially applying uneven pressure during the cuts. The track saw track should give you a dead straight line, but only if you aren't applying any lateral force during the entire cut.